Sharon L. Kirkman | Geology Reports

USGS1977

Catalog of earthquakes in the Santa Monica Mountains area for the period February 21, 1973 to December 31, 1973

The Seismological Laboratory of the California Institute of Technology(CALTECH) has reported instrumentally recorded earthquakes throughout southern California since 1932. Allen and others (1965) analyzed results from the Caltech seismograph network, and related earthquake data for the period from 1934 to 1963 to the regional geologic structures in southern California. A magnitude 6.0 earthquake occurred near Point Mugu, California, approximately 15 km southeast of Oxnard, on February 21, 1973. Within 20 hours of the main shock the U.S. Geological Survey (USGS) and the California Institute of Technology, Pasadena(CALTECH) began operation of temporary portable seismograph stations to study the aftershock sequence of the earthquake (Ellsworth and others, 1973). The temporary network of stations was replaced by an enlarged, permanent seismograph network beginning in June 1973. This catalog contains the fundamental parameters for earthquakes located within and adjacent to the seismograph network operated in the western Santa Monica Mountain region by the National Center for Earthquake Research (NCER), U. S. Geological Survey, during the period from February 21, 1973 to December 31, 1973 covering the main shock and aftershocks of the Pt. Mugu earthquake. The basic data contained in this catalog provides a foundation for further study of active tectonic processes in the western Santa Monica Mountains and adjacent areas.

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USGS1977

Catalog of earthquakes in the Santa Barbara Channel area for the period January 1, 1972 to December 31, 1973

The Santa Barbara Channel region forms the western most area of the Transverse Ranges, and is one of the most seismically active areas in the State of California. Instrumentally recorded earthquakes throughout southern California have been reported by the Seismological Laboratory of the California Institute of Technology (CALTECH) since 1932. Earthquake data for the period 1934 to 1963 were analyzed by Allen and others (1965) and related to regional geologic structures in southern California. Sylvester and others (1970) discussed the earthquake swarm that occurred in the Santa Barbara channel during the period from June 26 to August 3, 1968 with respect to the seismic history of the channel. The U. S. Geological Survey (USGS) (Vedder and others, 1969a) prepared a report on the geology, petroleum development, and seismicity of the Santa Barbara Channel region subsequent to an offshore oil-well blowout in the Dos Cuadras Offshore oil field. In that report, Hamilton and others (1969) reviewed the regional seismicity and its possible effects on the region. They noted that the existing seismic network precluded identification of individual active faults within the channel. A network of seismograph stations was established in late 1969 by the U. S. Geological Survey to monitor earthquakes in and around the Santa Barbara Channel. The purpose of this network is to provide data to gain insight into the tectonic and physical processes responsible for the generation of damaging earthquakes in the Santa Barbara Channel region. Lee and Vedder, (1973) reported the earthquakes located by this network for the period from January 1, 1970 to December 31, 1971, and showed that the earthquake activity appears to be spatially related to recognized faults in the region. This report contains a catalog of earthquakes in the Santa Barbara Channel region for the period from January 1, 1972 to December 31, 1973. It is prepared in a manner similar to that of the catalog contained in Lee and Vedder (1973) for the preceding two year period. These catalogs contain the basic study of seismicity in the Santa Barbara Channel region. The data contained in these catalogs provides a foundation for further study of the seismicity in tectonics of the Santa Barbara Channel region.

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